In the eastern calendar the Sunday after Pascha is named for St. Thomas.
Here's the reading from the Holy Gospel according St. John the Theologian and Evangelist:
19 Then, the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled, for fear of the Jews, Jesus came and stood in the midst, and said to them, “Peace be with you.” 20 When He had said this, He showed them His hands and His side. Then the disciples were glad when they saw the Lord. 21 So Jesus said to them again, “Peace to you! As the Father has sent Me, I also send you.” 22 And when He had said this, He breathed on them, and said to them, “Receive the Holy Spirit. 23 If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained.”
Seeing and Believing 24 Now Thomas, called the Twin, one of the twelve, was not with them when Jesus came. 25 The other disciples therefore said to him, “We have seen the Lord.” So he said to them, “Unless I see in His hands the print of the nails, and put my finger into the print of the nails, and put my hand into His side, I will not believe.” 26 And after eight days His disciples were again inside, and Thomas with them. Jesus came, the doors being shut, and stood in the midst, and said, “Peace to you!” 27 Then He said to Thomas, “Reach your finger here, and look at My hands; and reach your hand here, and put it into My side. Do not be unbelieving, but believing.” 28 And Thomas answered and said to Him, “My Lord and my God!” 29 Jesus said to him, “Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed.”
That You May Believe 30 And truly Jesus did many other signs in the presence of His disciples, which are not written in this book; 31 but these are written that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in His name. John 20:19-31 (NKJV)
[sources: http://oca.org/Reading.asp?SID=25&M=4&D=15&ReadingNum=3 , http://www.biblegateway.com/passage/?search=john%2020&version=50]